With the rapid development of electronic technology, electronic equipment marches rapidly towards aspects of functional diversification, information, integration and so on. The constantly increasing heat flux of electronic devices makes the large-scale application of the active thermal control system to be inevitable. A micro pump is exactly a key driving device of the active thermal control system. As an important research direction of the micro electro mechanical system, the micro mechanical pump is widely used in fields of drug transport system, electronic device cooling system, thermal control system, micro-chemical analysis system and the like.
Currently, the key technology of the micro-mechanical pump lies on: 1) cross-scale design which is achieved by combining and improving traditional pump design theories in a case of large scale difference between devices; 2) flow and thermal coupling, which require consideration of the feedback effect of both the heat production by the device and the heat dissipated in the system on the heat management system; 3) numerical simulation in which cross-scale flow and thermal problems in the flow field are accurately simulated; and 4) design for structure reliability, including leak proof design, anti-seismic design, shafting design and the like.
Currently, reliability has become a restriction factor in the micro pump. In the micro pump, the shafting, like a backbone, is especially responsible for reliability of the complete machine. As the only moving part of the micro pump, the shafting is designed to be stable and robust, which is the only means of prolonging service life of the complete machine. The bearings used in the micromechanical pumps are now divided into a mechanical contact bearing and a non-contact bearing. Due to the existence of bearing wear of the mechanical contact bearings, the service life of the micro-pump is seriously restricted. The non-contact bearing performs non-contact operation in the micro pump, which can greatly improve reliability and service life of the micro pump.
At present, the shafting suspension technology applied in the non-contact bearing mainly adopts the following means: active control suspension, permanent magnetic suspension, and hydraulic suspension. The basic principle of the active control suspension is that a position sensor captures dynamic position of a rotor and limits the rotor to the axle center through a dynamic magnetic field generated by a main control electromagnet. The active control suspension has advantages of high control precision and large load range, but also features a complex control circuit, a high price and increased additional power consumption. In the permanent magnetic suspension, the degree of freedom of the rotor is limited by repulsion of the permanent magnet. The permanent magnetic suspension has advantages of a simply and reliable structure and low assembly requirements, but cannot achieve suspension of full degrees of freedom without introducing external forces. In the hydraulic suspension, a high-pressure liquid film is generated on a suspension surface by high-speed rotation of a rotor to support suspension of the rotor. The structure is stable and reliable and has a small size, but is strict in machining and installation precision, and thus is difficult to machine and install.